The present disclosure relates to an ink-jet recording apparatus that achieves recording by ejecting ink onto a recording medium such as paper. More particularly, the present disclosure relates to a recording head recovery mechanism that, after forcibly expelling ink out of an ejection nozzle of a recording head, wipes off the purged ink stuck on an ink ejection surface with a wiper.
Recording apparatuses such as facsimile machines, copiers, and printers are configured to record images on a recording medium such as paper or OHP sheets. The recording methods they adopt are classified into ink-jet, wire-dot, thermal, and other methods. Ink-jet recording methods further divide into a serial type, in which recording proceeds while a recording head scans across a recording medium, and a line-head type, in which recording is performed with a recording head fixed to an apparatus body.
For example, an ink-jet recording apparatus of the line-head type is provided with, for each color, an ink-jet head (recording head) which has ejection nozzles arrayed at predetermined intervals across the entire width of the printing region, the width being perpendicular to the direction of transport of the recording medium. As the recording medium is transported, ink is ejected from the ejection nozzles that correspond to the printing position, achieving printing over the entire recording medium.
In such ink-jet recording apparatuses, a recording head can exhibit degraded printing performance due to unstraight ink trajectory (skew flying), ink ejection failure, etc. One cause is considered to be an abnormal meniscus resulting from the soiling of the ink ejection surface of the recording head with deposits, like foreign matter such as dust and powder of paper produced as paper is transported; fine ink droplets (hereinafter referred to as mist) which are ejected together with ink droplets for image recording; and mist splashed back when ink droplets land on the recording medium. Other causes are considered to include degraded air-tightness with a cap fitted, resulting from mist depositing and becoming dry where the cap is fitted; and the resulting increase in the viscosity of ink inside the nozzles.
As a solution, with a view to preventing the drying of ink inside ink ejection nozzles which have apertures on the ink ejection surface of the recording head, and preventing the clogging of the ink ejection nozzles resulting from increased viscosity of ink inside them, a configuration is adopted where, first, ink is forcibly expelled (purged) out of nozzles and, then, the purged ink stuck on the ink ejection surface (nozzle surface) is wiped off with a blade-form wiper, thereby to perform recording head recovery operation.
For example, according to one known method, a wiper is put in contact, under a predetermined contact pressure, with a part of a recording head's ink ejection surface where it has no nozzles to wipe the ink ejection surface. Specifically, as shown in FIG. 36A, a wiper 103 is pressed against, substantially perpendicular to, an ink ejection surface 101a of a recording head 101, in a region (wiping start position) outside a nozzle region 102 where ink ejection nozzles are arranged. Next, as shown in FIGS. 36B and 36C, the wiper 103 is moved horizontally across the ink ejection surface 101a in the direction indicated by arrow A to wipe off ink 104 in the nozzle region 102. Then, as shown in FIG. 36D, the wiper 103 is moved off the ink ejection surface 101a, and is then moved horizontally in the direction indicated by arrow A′ to return the wiper 103 to the wiping start position.
However, with the method shown in FIGS. 36A to 36D, when wiping is performed for the second time, ink 103a and 104a is stuck at the tip of the wiper 103 as shown in FIG. 37A. The ink 104b stuck at the tip of the wiper 103 has increased viscosity through exposure to air, and thus it then sticks to the ink ejection surface 101a as shown in FIGS. 37B and 37C.
On the other hand, in a known wiping mechanism for ink-jet recording apparatuses, two wipers are provided which can successively make contact with a recording head's ink ejection surface, the leading wiper wiping off purged ink, the following wiper wiping off ink left around the wiping start position of the leading wiper.